What is tax due on reverse tax ?

I think this might be the service tax payable on reverse charge basis(i.e. payable by service receiver).

N/N 30/2012 specifies some services on which the service tax is payable fully/partially by service receiver instead of service provider(e.g. GTA,Security,Legal services, etc)...

However, while paying tax under reverse charge mechanism, no CENV AT shall be availiable for making such payments.

Service Tax -CENVAT Credit = Total Service Tax Payable.

Tax on Reverse Charge is to be paid separately and no CENVAT Credit can be claimed on it.